CSU team continues to predict near-average Atlantic hurricane season

Colorado State University hurricane researchers continue to predict a near-average hurricane season for the Atlantic basin in 2016, citing two competing factors.

El Niño has just about dissipated and is likely to transition to weak La Niña conditions by this summer; however the far North Atlantic remains quite cold. The potential presence of a weak La Niña should reduce the strong upper-level westerly winds that were present in the Caribbean and across portions of the tropical Atlantic last season. However, the cold far North Atlantic often generates atmospheric conditions associated with increased sinking motion and stable air across the tropical Atlantic.

The CSU Tropical Meteorology Project team is predicting 12 named storms during the Atlantic hurricane season, which runs from June 1 to November 30. Of those, researchers expect five to become hurricanes and two to reach major hurricane strength (Saffir/Simpson category 3-4-5) with sustained winds of 111 miles per hour or greater. These forecast numbers do not include Hurricane Alex and Tropical Storm Bonnie, which formed prior to the official start of the hurricane season on June 1.

The team bases its forecasts on over 60 years of historical data that include Atlantic sea surface temperatures, sea level pressures, vertical wind shear levels (the change in wind direction and speed with height in the atmosphere), El Niño (warming of waters in the central and eastern tropical Pacific), and other factors.

So far, the 2016 hurricane season is exhibiting characteristics similar to 1973, 1978, 1983, 1992, and 2003.

“1973, 1978, 1983 and 1992 were below-average hurricane seasons, while 2003 had above-average activity,” said Phil Klotzbach, research scientist in the Department of Atmospheric Science and lead author of the report.

The team predicts that 2016 hurricane activity will be about 95 percent of the average season. By comparison, 2015’s hurricane activity was about 65 percent of the average season.

The CSU team will issue forecast updates on July 1 and August 4.

This is the 33rd year that the CSU hurricane research team has issued the Atlantic basin season hurricane forecast. The late William Gray, professor in the Department of Atmospheric Science for over 40 years, launched the report in 1984.

The CSU forecast is intended to provide a best estimate of activity to be experienced during the upcoming season – not an exact measure.

Klotzbach cautioned coastal residents to take proper precautions.

“It takes only one landfall event near you to make this an active season,” Klotzbach said.

The report also includes the probability of major hurricanes making landfall:

50 percent for the entire U.S. coastline (average for the last century is 52 percent)

30 percent for the U.S. East Coast including the Florida peninsula (average for the last century is 31 percent)

29 percent for the Gulf Coast from the Florida panhandle westward to Brownsville (average for the last century is 30 percent)

40 percent for the Caribbean (average for the last century is 42 percent)

The forecast team also tracks the likelihood of tropical storm-force, hurricane-force and major hurricane-force winds occurring at specific locations along the coastal United States, the Caribbean and Central America through its Landfall Probability website.

The site provides information for all coastal states as well as 11 regions and 205 individual counties along the U.S. coastline from Brownsville, Texas, to Eastport, Maine.

Landfall probabilities for regions and counties are adjusted based on the current climate and its projected effects on the upcoming hurricane season.

Klotzbach updates the site regularly with assistance from the GeoGraphics Laboratory at Bridgewater State University in Massachusetts.

Funding for this year’s report has been provided by Interstate Restoration, Ironshore Insurance, Macquarie Group and a grant from the G. Unger Vetlesen Foundation.

Extended range Atlantic Basin hurricane forecast for 2016:

(Released June 1, 2016)Tropical Cyclone Parameters Extended Range
(1981-2010 Climatological Median Forecast for 2016
in parentheses)
Named Storms (12)* 12
Named Storm Days (60.1) 50
Hurricanes (6.5) 5
Hurricane Days (21.3) 20
Major Hurricanes (2.0) 2
Major Hurricane Days (3.9) 4
Accumulated Cyclone Energy (92) 90
Net Tropical Cyclone Activity (103%) 95
* Numbers in ( ) represent medians based on 1981-2010 data. Forecast numbers do not include Alex and Bonnie which formed prior to the formal start of the Atlantic hurricane season on June 1.